@book{Howie1995,
  title = {Fundamentals of {{Semigroup Theory}}},
  author = {Howie, John M.},
  year = {1995},
  publisher = {Clarendon Press},
  address = {Oxford},
  isbn = {0-19-851194-9}
}

@article{Ibrahim2022,
  title = {On the Semigroup of Difunctional Binary Relations},
  author = {Ibrahim, Muhammad Jamilu and Sawudi, Ibrahim Mamman and Imam, Abdussamad Tanko},
  year = {2022},
  month = aug,
  journal = {FUDMA JOURNAL OF SCIENCES},
  volume = {6},
  number = {4},
  pages = {17--19},
  publisher = {Federal University Dutsin-Ma},
  doi = {10.33003/fjs-2022-0604-1026}
}

@article{ZS2077,
  title = {关于未来的研究},
  author = {赵四 and 王五},
  year = {2077},
  month = feb,
  journal = {自然},
  volume = {1},
  number = {1},
  pages = {1--1}
}